<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
   <style>
     #second {
        color: red;
     }
     .first .second {
        color: orangered;
     }
     * {
        font-size: 16px;
     }
     .first {
        font-size: 20px;
     }
   </style>
</head>
<body>
    <div class="first">
        <div class="second" id="second">66</div>
    </div>
</body>
</html>